1. Field of the Invention
The present invention relates to a connecting rod for use in reciprocating motion systems such as reciprocating internal combustion engines and a method for producing the same.
2. Description of the Prior Art
There are conventionally known such connecting rods for connecting a piston with a crankshaft in a reciprocating motion system, which include a larger diameter end portion broken and divided into a body side bearing half and a bearing cap, for example, as described in Japanese Patent Application Laid-open No. 37311/83.
In the production of such connecting rods, it is a conventional and common practice to make elongated notches or grooves only in the axially opposite end surfaces of the larger diameter end portion of the connecting rod product from the forging of a blank, at which notches or grooves the larger diameter end portion is ultimately intended to be broken and divided into sections, and then subjecting the notched or grooved part of the larger diameter end portion to a carburizing and quenching treatment for hardening. Thereafter, the resulting larger diameter end portion is broken and divided into a body side bearing half and a bearing cap, which parts are subsequently clamped together by connecting bolts, so that the bearing hole of the large diameter end portion can be finished. After such finishing, however, when split bearing metals are intended to be assembled to the respective semicircular bearing surfaces of the body side bearing half and the bearing cap, the reverses of the bearing metals may contact or bear the sharp inner edges of the broken and divided surfaces of the body side bearing half and the bearing cap and consequently, the reverses may be damaged or residual metal. In addition, the cut powder resulting from such cutting may remain on the broken and divided surfaces, where it may prevent the accurate re-assemblability of the parts of the larger diameter end portion.